465 lines
16 KiB
Python
465 lines
16 KiB
Python
"""
|
|
36. Generating HTML forms from models
|
|
|
|
Django provides shortcuts for creating Form objects from a model class and a
|
|
model instance.
|
|
|
|
The function django.newforms.form_for_model() takes a model class and returns
|
|
a Form that is tied to the model. This Form works just like any other Form,
|
|
with one additional method: save(). The save() method creates an instance
|
|
of the model and returns that newly created instance. It saves the instance to
|
|
the database if save(commit=True), which is default. If you pass
|
|
commit=False, then you'll get the object without committing the changes to the
|
|
database.
|
|
|
|
The function django.newforms.form_for_instance() takes a model instance and
|
|
returns a Form that is tied to the instance. This form works just like any
|
|
other Form, with one additional method: save(). The save()
|
|
method updates the model instance. It also takes a commit=True parameter.
|
|
|
|
The function django.newforms.save_instance() takes a bound form instance and a
|
|
model instance and saves the form's clean_data into the instance. It also takes
|
|
a commit=True parameter.
|
|
"""
|
|
|
|
from django.db import models
|
|
|
|
class Category(models.Model):
|
|
name = models.CharField(maxlength=20)
|
|
url = models.CharField('The URL', maxlength=40)
|
|
|
|
def __str__(self):
|
|
return self.name
|
|
|
|
class Writer(models.Model):
|
|
name = models.CharField(maxlength=50, help_text='Use both first and last names.')
|
|
|
|
def __str__(self):
|
|
return self.name
|
|
|
|
class Article(models.Model):
|
|
headline = models.CharField(maxlength=50)
|
|
pub_date = models.DateField()
|
|
created = models.DateField(editable=False)
|
|
writer = models.ForeignKey(Writer)
|
|
article = models.TextField()
|
|
categories = models.ManyToManyField(Category, blank=True)
|
|
|
|
def save(self):
|
|
import datetime
|
|
if not self.id:
|
|
self.created = datetime.date.today()
|
|
return super(Article, self).save()
|
|
|
|
def __str__(self):
|
|
return self.headline
|
|
|
|
class PhoneNumber(models.Model):
|
|
phone = models.PhoneNumberField()
|
|
description = models.CharField(maxlength=20)
|
|
|
|
def __str__(self):
|
|
return self.phone
|
|
|
|
__test__ = {'API_TESTS': """
|
|
>>> from django.newforms import form_for_model, form_for_instance, save_instance, BaseForm, Form, CharField
|
|
>>> import datetime
|
|
|
|
>>> Category.objects.all()
|
|
[]
|
|
|
|
>>> CategoryForm = form_for_model(Category)
|
|
>>> f = CategoryForm()
|
|
>>> print f
|
|
<tr><th><label for="id_name">Name:</label></th><td><input id="id_name" type="text" name="name" maxlength="20" /></td></tr>
|
|
<tr><th><label for="id_url">The URL:</label></th><td><input id="id_url" type="text" name="url" maxlength="40" /></td></tr>
|
|
>>> print f.as_ul()
|
|
<li><label for="id_name">Name:</label> <input id="id_name" type="text" name="name" maxlength="20" /></li>
|
|
<li><label for="id_url">The URL:</label> <input id="id_url" type="text" name="url" maxlength="40" /></li>
|
|
>>> print f['name']
|
|
<input id="id_name" type="text" name="name" maxlength="20" />
|
|
|
|
>>> f = CategoryForm(auto_id=False)
|
|
>>> print f.as_ul()
|
|
<li>Name: <input type="text" name="name" maxlength="20" /></li>
|
|
<li>The URL: <input type="text" name="url" maxlength="40" /></li>
|
|
|
|
>>> f = CategoryForm({'name': 'Entertainment', 'url': 'entertainment'})
|
|
>>> f.is_valid()
|
|
True
|
|
>>> f.clean_data
|
|
{'url': u'entertainment', 'name': u'Entertainment'}
|
|
>>> obj = f.save()
|
|
>>> obj
|
|
<Category: Entertainment>
|
|
>>> Category.objects.all()
|
|
[<Category: Entertainment>]
|
|
|
|
>>> f = CategoryForm({'name': "It's a test", 'url': 'test'})
|
|
>>> f.is_valid()
|
|
True
|
|
>>> f.clean_data
|
|
{'url': u'test', 'name': u"It's a test"}
|
|
>>> obj = f.save()
|
|
>>> obj
|
|
<Category: It's a test>
|
|
>>> Category.objects.all()
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
|
|
If you call save() with commit=False, then it will return an object that
|
|
hasn't yet been saved to the database. In this case, it's up to you to call
|
|
save() on the resulting model instance.
|
|
>>> f = CategoryForm({'name': 'Third test', 'url': 'third'})
|
|
>>> f.is_valid()
|
|
True
|
|
>>> f.clean_data
|
|
{'url': u'third', 'name': u'Third test'}
|
|
>>> obj = f.save(commit=False)
|
|
>>> obj
|
|
<Category: Third test>
|
|
>>> Category.objects.all()
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
>>> obj.save()
|
|
>>> Category.objects.all()
|
|
[<Category: Entertainment>, <Category: It's a test>, <Category: Third test>]
|
|
|
|
If you call save() with invalid data, you'll get a ValueError.
|
|
>>> f = CategoryForm({'name': '', 'url': 'foo'})
|
|
>>> f.errors
|
|
{'name': [u'This field is required.']}
|
|
>>> f.clean_data
|
|
Traceback (most recent call last):
|
|
...
|
|
AttributeError: 'CategoryForm' object has no attribute 'clean_data'
|
|
>>> f.save()
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: The Category could not be created because the data didn't validate.
|
|
>>> f = CategoryForm({'name': '', 'url': 'foo'})
|
|
>>> f.save()
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: The Category could not be created because the data didn't validate.
|
|
|
|
Create a couple of Writers.
|
|
>>> w = Writer(name='Mike Royko')
|
|
>>> w.save()
|
|
>>> w = Writer(name='Bob Woodward')
|
|
>>> w.save()
|
|
|
|
ManyToManyFields are represented by a MultipleChoiceField, and ForeignKeys are
|
|
represented by a ChoiceField.
|
|
>>> ArticleForm = form_for_model(Article)
|
|
>>> f = ArticleForm(auto_id=False)
|
|
>>> print f
|
|
<tr><th>Headline:</th><td><input type="text" name="headline" maxlength="50" /></td></tr>
|
|
<tr><th>Pub date:</th><td><input type="text" name="pub_date" /></td></tr>
|
|
<tr><th>Writer:</th><td><select name="writer">
|
|
<option value="" selected="selected">---------</option>
|
|
<option value="1">Mike Royko</option>
|
|
<option value="2">Bob Woodward</option>
|
|
</select></td></tr>
|
|
<tr><th>Article:</th><td><textarea rows="10" cols="40" name="article"></textarea></td></tr>
|
|
<tr><th>Categories:</th><td><select multiple="multiple" name="categories">
|
|
<option value="1">Entertainment</option>
|
|
<option value="2">It's a test</option>
|
|
<option value="3">Third test</option>
|
|
</select><br /> Hold down "Control", or "Command" on a Mac, to select more than one.</td></tr>
|
|
|
|
You can pass a custom Form class to form_for_model. Make sure it's a
|
|
subclass of BaseForm, not Form.
|
|
>>> class CustomForm(BaseForm):
|
|
... def say_hello(self):
|
|
... print 'hello'
|
|
>>> CategoryForm = form_for_model(Category, form=CustomForm)
|
|
>>> f = CategoryForm()
|
|
>>> f.say_hello()
|
|
hello
|
|
|
|
Use form_for_instance to create a Form from a model instance. The difference
|
|
between this Form and one created via form_for_model is that the object's
|
|
current values are inserted as 'initial' data in each Field.
|
|
>>> w = Writer.objects.get(name='Mike Royko')
|
|
>>> RoykoForm = form_for_instance(w)
|
|
>>> f = RoykoForm(auto_id=False)
|
|
>>> print f
|
|
<tr><th>Name:</th><td><input type="text" name="name" value="Mike Royko" maxlength="50" /><br />Use both first and last names.</td></tr>
|
|
|
|
>>> art = Article(headline='Test article', pub_date=datetime.date(1988, 1, 4), writer=w, article='Hello.')
|
|
>>> art.save()
|
|
>>> art.id
|
|
1
|
|
>>> TestArticleForm = form_for_instance(art)
|
|
>>> f = TestArticleForm(auto_id=False)
|
|
>>> print f.as_ul()
|
|
<li>Headline: <input type="text" name="headline" value="Test article" maxlength="50" /></li>
|
|
<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" /></li>
|
|
<li>Writer: <select name="writer">
|
|
<option value="">---------</option>
|
|
<option value="1" selected="selected">Mike Royko</option>
|
|
<option value="2">Bob Woodward</option>
|
|
</select></li>
|
|
<li>Article: <textarea rows="10" cols="40" name="article">Hello.</textarea></li>
|
|
<li>Categories: <select multiple="multiple" name="categories">
|
|
<option value="1">Entertainment</option>
|
|
<option value="2">It's a test</option>
|
|
<option value="3">Third test</option>
|
|
</select> Hold down "Control", or "Command" on a Mac, to select more than one.</li>
|
|
>>> f = TestArticleForm({'headline': u'New headline', 'pub_date': u'1988-01-04', 'writer': u'1', 'article': 'Hello.'})
|
|
>>> f.is_valid()
|
|
True
|
|
>>> new_art = f.save()
|
|
>>> new_art.id
|
|
1
|
|
>>> new_art = Article.objects.get(id=1)
|
|
>>> new_art.headline
|
|
'New headline'
|
|
|
|
Add some categories and test the many-to-many form output.
|
|
>>> new_art.categories.all()
|
|
[]
|
|
>>> new_art.categories.add(Category.objects.get(name='Entertainment'))
|
|
>>> new_art.categories.all()
|
|
[<Category: Entertainment>]
|
|
>>> TestArticleForm = form_for_instance(new_art)
|
|
>>> f = TestArticleForm(auto_id=False)
|
|
>>> print f.as_ul()
|
|
<li>Headline: <input type="text" name="headline" value="New headline" maxlength="50" /></li>
|
|
<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" /></li>
|
|
<li>Writer: <select name="writer">
|
|
<option value="">---------</option>
|
|
<option value="1" selected="selected">Mike Royko</option>
|
|
<option value="2">Bob Woodward</option>
|
|
</select></li>
|
|
<li>Article: <textarea rows="10" cols="40" name="article">Hello.</textarea></li>
|
|
<li>Categories: <select multiple="multiple" name="categories">
|
|
<option value="1" selected="selected">Entertainment</option>
|
|
<option value="2">It's a test</option>
|
|
<option value="3">Third test</option>
|
|
</select> Hold down "Control", or "Command" on a Mac, to select more than one.</li>
|
|
|
|
>>> f = TestArticleForm({'headline': u'New headline', 'pub_date': u'1988-01-04',
|
|
... 'writer': u'1', 'article': u'Hello.', 'categories': [u'1', u'2']})
|
|
>>> new_art = f.save()
|
|
>>> new_art.id
|
|
1
|
|
>>> new_art = Article.objects.get(id=1)
|
|
>>> new_art.categories.all()
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
|
|
Now, submit form data with no categories. This deletes the existing categories.
|
|
>>> f = TestArticleForm({'headline': u'New headline', 'pub_date': u'1988-01-04',
|
|
... 'writer': u'1', 'article': u'Hello.'})
|
|
>>> new_art = f.save()
|
|
>>> new_art.id
|
|
1
|
|
>>> new_art = Article.objects.get(id=1)
|
|
>>> new_art.categories.all()
|
|
[]
|
|
|
|
Create a new article, with categories, via the form.
|
|
>>> ArticleForm = form_for_model(Article)
|
|
>>> f = ArticleForm({'headline': u'The walrus was Paul', 'pub_date': u'1967-11-01',
|
|
... 'writer': u'1', 'article': u'Test.', 'categories': [u'1', u'2']})
|
|
>>> new_art = f.save()
|
|
>>> new_art.id
|
|
2
|
|
>>> new_art = Article.objects.get(id=2)
|
|
>>> new_art.categories.all()
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
|
|
Create a new article, with no categories, via the form.
|
|
>>> ArticleForm = form_for_model(Article)
|
|
>>> f = ArticleForm({'headline': u'The walrus was Paul', 'pub_date': u'1967-11-01',
|
|
... 'writer': u'1', 'article': u'Test.'})
|
|
>>> new_art = f.save()
|
|
>>> new_art.id
|
|
3
|
|
>>> new_art = Article.objects.get(id=3)
|
|
>>> new_art.categories.all()
|
|
[]
|
|
|
|
Here, we define a custom Form. Because it happens to have the same fields as
|
|
the Category model, we can use save_instance() to apply its changes to an
|
|
existing Category instance.
|
|
>>> class ShortCategory(Form):
|
|
... name = CharField(max_length=5)
|
|
... url = CharField(max_length=3)
|
|
>>> cat = Category.objects.get(name='Third test')
|
|
>>> cat
|
|
<Category: Third test>
|
|
>>> cat.id
|
|
3
|
|
>>> sc = ShortCategory({'name': 'Third', 'url': '3rd'})
|
|
>>> save_instance(sc, cat)
|
|
<Category: Third>
|
|
>>> Category.objects.get(id=3)
|
|
<Category: Third>
|
|
|
|
Here, we demonstrate that choices for a ForeignKey ChoiceField are determined
|
|
at runtime, based on the data in the database when the form is displayed, not
|
|
the data in the database when the form is instantiated.
|
|
>>> ArticleForm = form_for_model(Article)
|
|
>>> f = ArticleForm(auto_id=False)
|
|
>>> print f.as_ul()
|
|
<li>Headline: <input type="text" name="headline" maxlength="50" /></li>
|
|
<li>Pub date: <input type="text" name="pub_date" /></li>
|
|
<li>Writer: <select name="writer">
|
|
<option value="" selected="selected">---------</option>
|
|
<option value="1">Mike Royko</option>
|
|
<option value="2">Bob Woodward</option>
|
|
</select></li>
|
|
<li>Article: <textarea rows="10" cols="40" name="article"></textarea></li>
|
|
<li>Categories: <select multiple="multiple" name="categories">
|
|
<option value="1">Entertainment</option>
|
|
<option value="2">It's a test</option>
|
|
<option value="3">Third</option>
|
|
</select> Hold down "Control", or "Command" on a Mac, to select more than one.</li>
|
|
>>> Category.objects.create(name='Fourth', url='4th')
|
|
<Category: Fourth>
|
|
>>> Writer.objects.create(name='Carl Bernstein')
|
|
<Writer: Carl Bernstein>
|
|
>>> print f.as_ul()
|
|
<li>Headline: <input type="text" name="headline" maxlength="50" /></li>
|
|
<li>Pub date: <input type="text" name="pub_date" /></li>
|
|
<li>Writer: <select name="writer">
|
|
<option value="" selected="selected">---------</option>
|
|
<option value="1">Mike Royko</option>
|
|
<option value="2">Bob Woodward</option>
|
|
<option value="3">Carl Bernstein</option>
|
|
</select></li>
|
|
<li>Article: <textarea rows="10" cols="40" name="article"></textarea></li>
|
|
<li>Categories: <select multiple="multiple" name="categories">
|
|
<option value="1">Entertainment</option>
|
|
<option value="2">It's a test</option>
|
|
<option value="3">Third</option>
|
|
<option value="4">Fourth</option>
|
|
</select> Hold down "Control", or "Command" on a Mac, to select more than one.</li>
|
|
|
|
# ModelChoiceField ############################################################
|
|
|
|
>>> from django.newforms import ModelChoiceField, ModelMultipleChoiceField
|
|
|
|
>>> f = ModelChoiceField(Category.objects.all())
|
|
>>> f.clean('')
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'This field is required.']
|
|
>>> f.clean(None)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'This field is required.']
|
|
>>> f.clean(0)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. That choice is not one of the available choices.']
|
|
>>> f.clean(3)
|
|
<Category: Third>
|
|
>>> f.clean(2)
|
|
<Category: It's a test>
|
|
|
|
# Add a Category object *after* the ModelChoiceField has already been
|
|
# instantiated. This proves clean() checks the database during clean() rather
|
|
# than caching it at time of instantiation.
|
|
>>> Category.objects.create(name='Fifth', url='5th')
|
|
<Category: Fifth>
|
|
>>> f.clean(5)
|
|
<Category: Fifth>
|
|
|
|
# Delete a Category object *after* the ModelChoiceField has already been
|
|
# instantiated. This proves clean() checks the database during clean() rather
|
|
# than caching it at time of instantiation.
|
|
>>> Category.objects.get(url='5th').delete()
|
|
>>> f.clean(5)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. That choice is not one of the available choices.']
|
|
|
|
>>> f = ModelChoiceField(Category.objects.filter(pk=1), required=False)
|
|
>>> print f.clean('')
|
|
None
|
|
>>> f.clean('')
|
|
>>> f.clean('1')
|
|
<Category: Entertainment>
|
|
>>> f.clean('100')
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. That choice is not one of the available choices.']
|
|
|
|
# ModelMultipleChoiceField ####################################################
|
|
|
|
>>> f = ModelMultipleChoiceField(Category.objects.all())
|
|
>>> f.clean(None)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'This field is required.']
|
|
>>> f.clean([])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'This field is required.']
|
|
>>> f.clean([1])
|
|
[<Category: Entertainment>]
|
|
>>> f.clean([2])
|
|
[<Category: It's a test>]
|
|
>>> f.clean(['1'])
|
|
[<Category: Entertainment>]
|
|
>>> f.clean(['1', '2'])
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
>>> f.clean([1, '2'])
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
>>> f.clean((1, '2'))
|
|
[<Category: Entertainment>, <Category: It's a test>]
|
|
>>> f.clean(['100'])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. 100 is not one of the available choices.']
|
|
>>> f.clean('hello')
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Enter a list of values.']
|
|
|
|
# Add a Category object *after* the ModelChoiceField has already been
|
|
# instantiated. This proves clean() checks the database during clean() rather
|
|
# than caching it at time of instantiation.
|
|
>>> Category.objects.create(id=6, name='Sixth', url='6th')
|
|
<Category: Sixth>
|
|
>>> f.clean([6])
|
|
[<Category: Sixth>]
|
|
|
|
# Delete a Category object *after* the ModelChoiceField has already been
|
|
# instantiated. This proves clean() checks the database during clean() rather
|
|
# than caching it at time of instantiation.
|
|
>>> Category.objects.get(url='6th').delete()
|
|
>>> f.clean([6])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. 6 is not one of the available choices.']
|
|
|
|
>>> f = ModelMultipleChoiceField(Category.objects.all(), required=False)
|
|
>>> f.clean([])
|
|
[]
|
|
>>> f.clean(())
|
|
[]
|
|
>>> f.clean(['10'])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
|
|
>>> f.clean(['3', '10'])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
|
|
>>> f.clean(['1', '10'])
|
|
Traceback (most recent call last):
|
|
...
|
|
ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
|
|
|
|
# PhoneNumberField ############################################################
|
|
|
|
>>> PhoneNumberForm = form_for_model(PhoneNumber)
|
|
>>> f = PhoneNumberForm({'phone': '(312) 555-1212', 'description': 'Assistance'})
|
|
>>> f.is_valid()
|
|
True
|
|
>>> f.clean_data
|
|
{'phone': u'312-555-1212', 'description': u'Assistance'}
|
|
"""}
|